Focuses on the enhancement of chemistry students' skill in problem solving utilizing problem categorization techniques. Indicates that explicit training in categorization skills can lead to higher achievement in complex problem-solving situations but that such achievement may be limited by the lack of linkages between students' conceptual…

A 1-year lag was found between the effect of an intervention intended to promote formal operational thinking in students initially 11 or 12 years of age and the appearance of substantial science achievement in the experimental groups. A one-year lag on cognitive development and an age/gender interaction were also reported. (Author/KR)